Search

Cobalt phthalocyanine (CoPc) has drawn increasing attention in CO2 electroreduction to CO due to its clear coordination structure (Co–N4–C) and high selectivity. However, its performance is severely restrained by its poor stability and low conductivity. Herein, a promising catalyst for dispersing CoPc on three-dimensional porous carbon (PC) was prepared via a pyrolysis procedure using NaCl as the template. Benefiting from the high intrinsic activity and large exposure of active sites, as well as the unique carbon architecture with facilitated mass transportation, the derived CoPc/PC catalyst shows impressive performance for CO2 electroreduction. The CO faradaic efficiency achieves a maximum value of 95% accompanied by a CO partial current density of 20.5 mA cm−2. The study paves a new avenue for the fabrication of high-efficiency molecular catalysts for CO2 conversion. [ABSTRACT FROM AUTHOR]

Developing efficient electrocatalysts for CO 2 electroreduction to syngas with a specific H 2 /CO ratio over a wide potential window is desperately required but still challenging. In this work, a series of dual-site catalysts composed of iron phthalocyanine (FePc) and ∼18 nm Cobalt nanoparticles (Co NPs) anchored on N-doped carbon matrix has been constructed from zeolitic imidazolate framework-67 (ZIF-67). Benefiting from the synergistic effect of FePc and Co NPs, the derived FePc/Co@N–C catalyst shows impressive capability for CO 2 electrolysis to syngas. By varying the pyrolysis temperatures (600–800 °C) of ZIF-67 and the mass ratio of Co@N–C to FePc (1–3), an adjustable H 2 /CO ratio of 2–4 is obtained, and the value can be maintained stable within a potential window of −0.66 to −0.86 V vs. RHE in an H-type cell. Moreover, this electrocatalyst exhibits favorable stability without distinct performance decay. When conducted in a flow cell, an enhanced catalytic activity is demonstrated with an industrial current density (>100 mA cm−2) at −0.8 V vs. RHE and a steady H 2 /CO ratio of 2 from −0.4 to −0.6 V vs. RHE. This work provides a promising strategy of designing bifunctional electrocatalysts for syngas generation with stable H 2 /CO ratio across a wide potential range. [Display omitted] • Dual-site electrocatalyst composed of FePc and Co NPs is constructed for CO 2 electrolysis to syngas. • High activity, adjustable H 2 /CO ratio (2–4) and favorable stability are demonstrated. • The syngas with specific H 2 /CO ratio can be achieved over a wide potential range. • The synergistic effect of FePc and Co NPs accounts for the impressive performance for CO 2 electrolysis. [ABSTRACT FROM AUTHOR]

Electrochemical CO 2 reduction (ECR) has been considered as the most promising route to convert CO 2 into fuels, but suffers inferior conversion efficiency and product selectivity due to the lack of effective electrocatalysts. Herein, the N-coordinated single-atomic Ni active sites embedded in porous carbon nanotubes (Ni/N-CNTs) are constructed through one-pot pyrolysis strategy as an efficient ECR electrocatalyst. The Zn source in pyrolysis plays a key role in the formation of bamboo-like CNTs, and increased concentrations of surface defects and single-atomic Ni sites of the electrocatalyst. All these benefits endow the electrocatalyst with excellent ECR performance, achieving a large CO Faradaic efficiency (FE CO) up to 98% and turnover frequency up to 304.5 h−1 at a relatively low potential of −0.65 V vs. RHE. Furthermore, over 80% FE CO can be maintained in a wide potential range from −0.57 to −0.81 V. In addition, the electrocatalyst also shows high operation stability for 20 h without obvious FE CO and j CO decay. We believe this study will shed a new light on the design of highly efficient M/N–C catalyst for ECR systems. [Display omitted] • Single-atomic nickel active sites in carbon nanotubes is developed via Zn-assisted pyrolysis method. • High performance for electrochemical CO 2 reduction with CO Faradaic efficiency of 98% at a overpotential of 540 mV. • Improved nanotubular morphology, increased concentrations of defects and single Ni active sites achieved by Zn addition. • Unveiling the decisive catalytic effect of single-atomic Ni sites in catalyzing CO2 electroreduction. [ABSTRACT FROM AUTHOR]

• Highly dispersed Ni species supported on mesoporous nitrogen-doped carbon are fabricated via simple confined pyrolysis strategy. • The confinement agent citric acid is quite requisite for dispersing ni species and forming mesoporous graphene-like carbon substrate. • High activity and stability are demonstrated for both HER and OER. • Unveiling the coupling effect of Ni nanoparticles (3 nm) and ni-nx sites in catalyzing HER and OER. Developing an efficient and low-cost bifunctional electrocatalysts with superior activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly required but still challenging. Herein, highly dispersed Ni species containing both Ni nanoparticles (NPs) and atomically dispersed Ni-N X on mesoporous nitrogen-doped carbon (Ni-N-C) were prepared by a facile one-pot pyrolysis strategy using dicyandiamide, citric acid and nickel acetylacetonate as raw materials. The confinement agent citric acid is quite requisite for dispersing Ni NPs and forming mesoporous graphene-like carbon substrate. Due to the uniform size of Ni NPs (3 nm) and the synergistic effect between Ni NPs and Ni-N X , and the unique mesoporous carbon structure, such Ni-N-C catalyst exhibits favorable activities for both HER and OER. The overpotentials for HER and OER are only 218 and 330 mV vs. RHE on glassy carbon to deliver a current density of 10 mA·cm−2, respectively. Moreover, this catalyst also showed good operation durability with no obvious deactivation after long-term (18 h) potentiostatic electrolysis or continuous CV tests. This work could offer a new avenue for the design of bifunctional electrocatalysts in efficient water splitting. [Display omitted] [ABSTRACT FROM AUTHOR]

A biosensor based on the plasma polyaniline (pPANI)-modified tin oxide and 3D reduced graphene oxide (SnO 2 @3D-rGO) nanocomposite was fabricated to detect glucose. The SnO 2 @3D-rGO nanocomposite was synthesized by simultaneously reducing 3D graphene oxide (3D-GO) and translating SnCl 4 into SnO 2 , followed by pPANI modification. The content of amino groups in the SnO 2 @3D-rGO@pPANI nanocomposites depended on the plasma input powers used in plasma deposition. The SnO 2 @3D-rGO nanocomposite was important in the electrochemical biosensor to detect glucose. The fabricated biosensor exhibited a much higher sensitivity than that formed from individual components, namely, SnO 2 @3D-rGO and pPANI. This biosensor demonstrated a low detection limit of 0.047 ng mL −1 (0.26 nM) (S/N = 3) within the concentration range of 0.1 ng mL −1 to 5 μg mL −1 . The selectivity, stability, and practicality of the SnO 2 @3D-rGO@pPANI-based biosensor were observed. In conclusion, the plasma surface-modified nanocomposite is a promising candidate as biosensor for glucose detection and biological diagnosis. [ABSTRACT FROM AUTHOR]

Abstract: One-dimensional semiconductor nanostructures have demonstrated significant advantages for electrochemical electrode due to their remarkable size-dependent and structure-related properties. In this work, large-scale single-crystalline SnO2 nanowires have been successfully synthesized by thermal evaporation of a SnO2 and C powder under atmospheric conditions without any carrier gas or noble metal catalysts-coated substrate. The as-prepared samples exhibit uniform morphology with a thin diameter of 100–200 nm and length up to several tens of micrometers. The SnO2 nanowires directly grown on the initially deposition layer are found to grow along [301] direction, which is possibly dominated by a vapor–solid (VS) mechanism. The SnO2 nanowires synthesized by this simple and cheap method deliver a very high lithium storage capacity with good cycle stability and high rate capability, allowing for the achievement of high energy density and long cycle life for the next-generation energy conversion and storage devices. [Copyright &y& Elsevier]

Abstract: A novel AB5-alloy oxide/graphene composite has been fabricated through a facile mixing of commercial oxidized AB5-alloy and graphene as anode materials for lithium ion batteries. Electrochemical measurements show that the composite delivers an initial discharge capacity of 1639.7mAhg−1 and maintains a high reversible capacity of 418.2mAhg−1 up to 180 cycles. The enhanced cycling stability could be attributed to the fact that AB5-alloy oxide/graphene composite can accommodate large volume change during cycling and maintain good electronic contact. [Copyright &y& Elsevier]

Electrocatalytic reduction of CO 2 into syngas (CO and H 2) has been recognized to be a promising approach to achieve carbon neutrality. However, producing syngas with tunable H 2 /CO ratios in a wide range is still challenging. Herein, nitrogen doped graphene aerogel (GA) supported both single-atomic Ni and Ni nanoparticles (NPs) with a surface atomic ratio of 1.11 were constructed by using layered double hydroxide (LDHs) and g-C 3 N 4 as Ni and N precursors, respectively. H 2 and CO are the only products of CO 2 electroreduction and the ratio of H 2 /CO can be tuned from 0.4 to 2.5 by changing applied potentials. In addition, the catalyst exhibits a large CO Faradaic efficiency (74%) and good long-term stability (12 h) at a relatively small potential (−0.67 V vs. RHE). This study will shed a new light on the construction of bifunctional catalysts for efficient tunable syngas generation via electroreduction of CO 2. [Display omitted] • N doped graphene aerogel supported Ni electrocatalysts were constructed. • Both single-atomic Ni and Ni nanoparticles were contained in the electrocatalyst. • High catalytic performance for electrochemical CO 2 reduction to tunable syngas. • The decisive role of Ni nanoparticles and single Ni sites in catalyzing H 2 O and CO 2. [ABSTRACT FROM AUTHOR]

Single-atom transition-metal-anchored nitrogen-doped carbon (M-N-C) materials show great potential in electrochemical reduction of CO 2 to CO. However, the development of catalysts with high exposure density of M-N x active sites remains key challenge. Herein, we report an atomically dispersed and highly exposed Fe coordinated to nitrogen (Fe-N x) active sites doped within carbon nanorods (Fe–N–C) by pyrolysis of sea urchin-like FeOOH-polyaniline (FeOOH-PANI) composite. Results from X-ray photoelectron spectra (XPS) and operando X-ray absorption fine structure (XAFS) spectra confirmed the atomically dispersed Fe species and indicated the Fe coordinated with four N atoms to form the highly exposed Fe-N x active sites. Detailed examination of the Fe–N–C electrocatalyst reveals a high selectivity for CO 2 reduction, presenting CO Faradaic efficiency (FE CO) of 95% with CO partial current density (j CO) of 1.9 mA cm−2 at a relatively low overpotential of 530 mV. The high-performance is a result of the porous structure of catalyst with highly exposed Fe-N x active sites, as well as the larger specific surface area and electrochemical active surface area. Our work proposes an effective and feasible way to designing M-N-C catalysts for efficient electrochemical reduction of CO 2. [ABSTRACT FROM AUTHOR]

In order to increase the working voltage of the aqueous zinc ion batteries with manganese-based material as the positive electrode material, an ultrathin nanosheet array (MnCO3 NA) was grown on a nickel foam substrate by a one-step solvothermal method. The structure, morphology and electrochemical properties of MnCO3 NA were characterized by X-ray diffraction (XRD), scanning electron microscope, transmission electron microscope and battery performance tester. The experiments results showed that the thickness of the MnCO3 NA was about 30 nm and the height was about 500 nm. It was directly applied to the zinc ion battery in the alkaline electrolyte, delivering a high working voltage of 1. 73 V, a specific discharge capacity of 255. 41 mAh/g at 0. 1 A/g, and a capacity retention of 83. 1% after 270 charge-discharge cycles at 0. 5 A/g. In addition, the zinc storage mechanism of the electrode was a mono-phase reaction from Mn2+ to Mn3+, which was analyzed by ex-situ XRD and photoelectron spectroscopy at different potential states. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is a long-lived stratospheric ozone-depleting substance with an atmospheric lifetime of 116 years. It is also a greenhouse gas with a global warming potential value of about 310. Due to its high kinetic stability and thermal decomposition temperature exceeding 1000°C, the treatment and recovery of nitrous oxide pose significant engineering and climate challenges. In this study, we introduce a Cu–Fe oxide catalyst that demonstrates efficient and low-temperature conversion of N2O to N2 using readily available reductant CO. The oxide catalyst was synthesized by a solvothermal method and a "from bottom to top" technique. Characterizations by X-ray diffraction (XRD), CO temperature-programmed desorption (C-O‑TPD), scanning electron microscopy (SEM), and BET indicate that the catalyst with weaker CO adsorption sites, fewer strong CO adsorption sites, suitable particle size, good dispersion and high specific surface area performs excellent reaction activity in the reduction of N2O to N2 by CO. The active site of Cu is stronger, and the addition of Fe can promote dispersion of the Cu active site and increase the exposure to the active site. A new approach has been proposed to address nitrous oxide emissions, a greenhouse gas with high thermodynamic stability, in the chemical industrial process that generates nitrous oxide as a byproduct. [ABSTRACT FROM AUTHOR]

[Display omitted] • An operando crystal-amorphous transformation of VOOH is demonstrated via in-situ / ex-situ structural analyses. • The unique crystal-amorphous transformation allows the obtained amorphous V 2 O 5 to achieve the high capacity, superior rate performance, and high energy and power densities. • The potentiality of cathode materials via operando crystal-amorphous transformation to achieve the enhanced zinc storage is confirmed. Aqueous zinc-ion batteries have obtained broad attention due to their high safety, eco-friendliness, and low cost. However, they are still in the developing stage considering the limited candidate of high-performance cathode materials. Furthermore, the intrinsic storage zinc mechanism is also needed to uncover. Here, we propose an operando crystal-amorphous transformation of tunnel-type VOOH and the obtained amorphous V 2 O 5 serves as a high-performance zinc-ion battery cathode. In-situ X-ray diffraction corroborates the unique operando crystal-amorphous transformation of VOOH during the initial charging process. X-ray photoelectron spectroscopy and transmission electron microscopy further demonstrate the element valence evolution and the lattice structure change, respectively. The operando electrochemical crystal-amorphous transformation allows the obtained amorphous V 2 O 5 to achieve the high capacity of ∼ 350.7 mAh g−1, rate performance (151.2 mAh g−1 at 6.4 A g−1), energy and power densities (137 Wh kg−1 at 6831 W kg−1), unveiling a promising approach of cathode materials via operando crystal-amorphous transformation to achieve the enhanced zinc storage. [ABSTRACT FROM AUTHOR]

As to the issue that the quality and market application of waste tires derived pyrolytic carbon derived from waste tires directly affect the economy of the pyrolysis process, the pyrolysis techndogy, main influencing factors and recycle utilization of pyrolytic carbon were reviewed. It was found that the pyrolysis of waste was a complex process, which was mainly affected by pyrolysis temperature, heating rate, operating pressure and rection time. The rate of carbon content of pyrolytic carbon of more than 80%. It has been widely used in the preparation of active carbon, the rubber reinforcing agent, the asphalt modifier, the battery and ink materials, etc. In the future, the pyrolysis system of waste tires should be further optimized, and the pyrolysis mechanism and kinetics process should be further studied to realize the precise control of the pyrolysis. Meanwhile, the integrated technology integratingwaste tires pretreatment, pyrolysis and pyrolytic carbon deep processing should be developed to further improve the quality of pyrolytic carbon and broaden its applications, finally realizing the efficient utilization of pyrolytic carbon. [ABSTRACT FROM AUTHOR]

• The MoS 2 /V 2 O 5 composite cathode is successfully constructed by one-step ball milling. • The unique in-situ conversion mechanism allows the obtained MoO 3 /V 2 O 5 cathode to achieve superior electrochemical performance. • The potentiality of rapidly constructing composite cathodes by ball milling is confirmed. Aqueous zinc-ion batteries have advantages of high safety, friendly environment, low cost, and can be applied to large-scale energy storage. To prepare high-performance cathode materials easily and quickly is still one of the development directions. Based on the principle that two-dimensional layered materials can be thinned layer-by-layer via mechanical force, the molybdenum disulfide (MoS 2)-based cathodes are prepared by one-step ball milling. The shear force and shockwave generated during ball milling effectively promote the preparation of MoS 2 /V 2 O 5 cathode materials. X-ray diffraction, Raman, and infrared tests confirm the presence of both MoS 2 and V 2 O 5 components in the prepared MoS 2 /V 2 O 5. The presence of metallic phase 1T-MoS 2 in the MoS 2 /V 2 O 5 is confirmed by X-ray photoelectron spectroscopy and transmission electron microscopy. Via a charging conversion mechanism, the obtained MoO 3 /V 2 O 5 cathode has a high capacity of 417.4 mAh g −1, good rate performance (83.6 mAh g −1 at 10 A g −1), high energy and power densities (83.6 Wh kg−1 at 10,032 W kg−1). This study provides a new idea for constructing two-dimensional material-based cathodes by ball milling. [Display omitted] [ABSTRACT FROM AUTHOR]

Research on aqueous zinc‐ion batteries is still in its initial stages owing to the limited choice of cathode materials, especially those having tunnel structures with high capacity and fast kinetics. Furthermore, their zinc ion storage mechanisms are not well established as yet. Here, a novel in situ electrochemical lattice distortion of vanadium trioxide (V2O3) is demonstrated. The obtained defect‐rich V2O3 is applied as a cathode for ultrafast Zn2+ storage. Operando X‐ray diffraction and operando Raman spectroscopy corroborate the unique lattice conversion reaction of V2O3 during the initial charging process. Transmission electron microscopy and X‐ray photoelectron spectroscopy further demonstrate the stability of the main crystal planes of V2O3 during the initial lattice distortion and subsequent zinc ion storage processes. This unique in situ electrochemical lattice conversion reaction allows V2O3 to achieve a high capacity of 382.5 mAh g−1, remarkable rate performance (154.3 mAh g−1 at 51.2 A g−1), and high energy and power densities (139 Wh kg−1 at 46 KW kg−1), revealing the potential of tunnel‐type cathodes via an in situ electrochemical lattice distortion reaction to achieve ultrafast zinc ion storage with high capacity. [ABSTRACT FROM AUTHOR]

A series of multicomponent Co 9 S 8 @MoS 2 nanohybrids derived from cobalt-doped polyoxometalate (Co-POMs) by modulating the precursor ratios of H 5 Mo 12 O 41 P (PMo 12) to Co(NO 3) 2 was synthesized and utilized as a bifunctional electrocatalyst for a non-Pt methanol oxidation reaction and overall water splitting in alkaline solution. In view of the importance of multifunctional catalysts that can drive different electrocatalytic reactions in the same electrolyte solution, we designed and prepared a series of multicomponent nanohybrids composed of Co 9 S 8 and MoS 2 derived from cobalt-doped polyoxometalate (Co-POMs) by one-pot calcination method. The obtained Co 9 S 8 @MoS 2 nanohybrids were composed of Co 9 S 8 , MoS 2 , Co-Mo-S phases and assembled nanosheets, and therefore were explored as trifunctional electrocatalysts for hydrogen evolution reaction, oxygen evolution reaction, and methanol oxidation reaction (MOR) in an alkaline medium. The nanostructure and chemical components of the series of Co 9 S 8 @MoS 2 nanohybrids can be modulated by changing the mole ratios of H 5 Mo 12 O 41 P to Co(NO 3) 2 precursor. Compared with the sole component and other reported Co 9 S 8 @MoS 2 nanohybrids, the Co 9 S 8 @MoS 2 nanohybrid prepared from the 1:1 ratio of PMo 12 and Co(NO 3) 2 exhibited superior MOR catalysis efficiency (121.4 mA cm−2) and an extremely low overpotential (1.49 V) for overall water splitting at a current density of 10 mA cm−2 owning to the effective synergism among Co 9 S 8 , MoS 2 , and Co-Mo-S phase. Overall, this study provides a feasible approach to developing efficient and stable trifunctional bimetal electrocatalysts for clean-energy applications. [ABSTRACT FROM AUTHOR]

A 3D porous graphene composite film containing Ni/NiO hybrid nanoparticles (Ni/NiO NPs) is prepared by combining electrophoresis deposition and thermal H2 annealing techniques. The Ni/NiO NPs with a mean diameter of 45 nm are uniformly embedded on both the exterior and interior surfaces of reduced graphene, forming a 3D porous reduced graphene oxide composite film (Ni/NiO rGO). The insertion of Ni/NiO NPs into rGO greatly improves the electric conductivity and charge storage capability of the resultant Ni/NiO rGO film. By directly using it as freestanding electrodes, the fabricated lithium-ion battery and supercapacitor respectively exhibited high capacities of 758 mAh g−1@ 0.2 A g−1 and 430.8 F g−1@0.5 A g−1, an increase of 82.3-fold and 20.2-fold compared to the pure rGO electrode-based counterparts under the same condition. [ABSTRACT FROM AUTHOR]

A novel nanocomposite composed of a bimetallic CoNi-zeolitic imidazole framework embedded by MoS 2 nanosheets (MoS 2 @CoNi-ZIF) was synthesized as a bifunctional electrocatalyst for both non-Pt methanol oxidation reaction (MOR) and overall water splitting in an alkaline solution. • Bimetallic CoNi-zeolitic imidazole framework embedded by MoS 2 nanosheets as bifunctional electrocatalyst. • Multiple functionally catalytic performances for MOR and water splitting in an alkaline solution. • Feasible synthesis without requiring calcination or other treatments. • Strong synergistic effect providing the MoS 2 @CoNi-ZIF catalyst with a comprehensive performance and high stability. We have explored a nanocomposite composed of a bimetallic CoNi-zeolitic imidazole framework embedded by MoS 2 nanosheets (MoS 2 @CoNi-ZIF), as a bifunctional electrocatalyst for non-Pt methanol oxidation reaction (MOR) and overall water splitting in an alkaline solution. The series of MoS 2 @CoNi-ZIF nanocomposites exhibit different catalytic activities. Significantly, the MoS 2 @CoNi-ZIF nanosheet with a ratio of MoS 2 :CoNi-ZIF = 3:1 (MoS 2 @CoNi-ZIF(3-1)) shows the excellent electrocatalytic activity for MOR, affording an oxidation potential at 1.6 V, also with high catalytic current density and durability. Moreover, the MoS 2 @CoNi-ZIF(3-1) nanocomposite shows a superior electrocatalytic performance toward HER and OER. When the MoS 2 @CoNi-ZIF(3-1) was applied as the bifunctional catalyst for both the anode and cathode, the voltage applied to a two-electrode cell is 1.55 V to achieve a current density of 10 mA cm−2 for overall water splitting. This work provides a promising electrocatalyst for developing high-performance non-Pt-based clean energy and fuel cells in alkaline solution. [ABSTRACT FROM AUTHOR]

The nano‐oxide materials with special structures prepared by template methods have a good dispersion, regular structures and high specific surface areas. Therefore, in some areas, improved properties are observed than conventional bulk oxide materials. For example, in the treatment of dye wastewater, the treatment efficiency of adsorbents and catalytic materials prepared by template method was about 30 % or even higher than that of conventional samples. This review mainly focuses on the progress of inorganic, organic and biological templates in the preparation of micro‐ and nano‐ oxide materials with special morphologies, and the roles of the prepared materials as adsorbents and photocatalysts in dye wastewater treatment. The characteristics and advantages of inorganic, organic and biological template are also summarized. In addition, the applications of template method prepared oxides in the field of sensors, drug carrier, energy materials and other fields are briefly discussed with detailed examples. [ABSTRACT FROM AUTHOR]

• Zeolitic imidazolate framework-8 (Zif-8) was prepared by a facile microwave hydrothermal method. • The N doped ZnO was synthesized by one-step controllable pyrolysis of Zif-8. • The N doped ZnO exhibited a higher photocatalytic degradation of methylene blue (MB) under solar-simulated light. The precursor particles were successfully prepared by a facile microwave hydrothermal method. Compared with solvothermal and precipitation method, microwave hydrothermal method can greatly shorten the reaction time and increase the product yields. Nitrogen (N) doped zinc oxide (ZnO) nanoparticles were derived via one-step controllable pyrolysis of zeolitic imidazolate framework-8 (Zif-8) precursors under 550 °C. The powder X-ray diffraction (XRD) analysis, elemental mapping image, energy dispersive spectrometry (EDS) spectra and X-ray photoelectron spectroscopy (XPS) analysis proved that Zif-8 particles were converted to ZnO and the N atoms were successfully doped into ZnO lattice. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results demonstrated that N doped ZnO retained the morphology of Zif-8 with a particle size of approximately ~70 nm and the UV–visible diffuse reflectance spectra (UV–vis DRS) showed that the as-prepared N doped ZnO possessed a lower band gap (3.16 eV) than commercial ZnO (3.26 eV). The photocatalytic activities of the as-prepared samples were evaluated by the degradation rate of methylene blue (MB) upon irradiation with solar-simulated light. The photocatalytic degradation efficiency of N doped ZnO was 95.3% after 80 min illumination, which was much higher than that of other samples prepared by other methods. Quenching tests proved that the photo-generated holes (h+) played a main role in the photodegradation of MB under solar-simulated light irradiation. [ABSTRACT FROM AUTHOR]

With the rapid development of industry and agriculture and the greatly improved living conditions, the resultant gradually deteriorated environments threaten the human beings. Refractory or even toxic pollutants, which are from different industries such as printing and dyeing, pesticides, chemicals, petrochemicals, plastics and rubber, seriously threat the ecosystems and human health. Having the advantages of flexible composition, unique structure, high stability, memory effect, easy preparation and low cost, hydrotalcite compounds have a great potential in sewage degradation and environmental protection. This study focuses on the adsorption and catalytic properties (such as photocatalysis, electrocatalysis and photoelectrocatalysis) of hydrotalcite‐derived materials for treating organic, inorganic and heavy metal ion sewage. The types of adsorption and catalysis, and the effects of various influencing factors on the degradation efficiency were discussed as well. [ABSTRACT FROM AUTHOR]

Cellulose aerogels are a new category of high-efficiency adsorbents for treating oil spills and water pollution. However, the hydrophilic properties and recyclability of aerogels after adsorption hamper developments and applications. Combining both hydrophobic and magnetic properties are expected to improve their adsorption capacity and functionality. In this study, the effect of oleic acid (OA) and nanomagnetite on the preparation of magnetic nanocellulose aerogels (called as NCA/OA/Fe 3 O 4) by a mechanical mixing combined with freeze-drying method have been investigated. It has been found that the optimal condition for fabricating this NCA/OA/Fe 3 O 4 aerogel is 0.4 wt% nanocellulose, 3 mg mL−1 OA and 0.5 wt% Fe 3 O 4 in the aqueous solution. This aerogel has a very low density of 9.2 mg cm−3 and demonstrates a high adsorption capacity of 68.06 g g−1 for cyclohexane. In addition, this aerogel adsorbent demonstrates an excellent magnetic responsivity and can be easily recycled by a permanent magnet after adsorption. As a consequence, this hydrophobic magnetic NCA/OA/Fe 3 O 4 aerogel is promising not only for easy oil and organic solvent adsorption but also potentially for other magnetic related applications. [ABSTRACT FROM AUTHOR]

• B-doping carbon nanodots (B-C-dots) were decorated on the surface of C 3 N 4. • Effectively enhanced photocatalytic activity was observed on B-C-dots decorated C 3 N 4. • The type-II heterojunction of C 3 N 4 and B-C-dots improved the photocatalytic activity. • Effect of B doping level of C-dots on the photocatalytic activity was investigated. Decorating electron-accepting materials on carbon nitride (C 3 N 4) is a promising strategy to construct heterostructure catalysts for improved photocatalytic abilities. In this study, B-doped carbon-dots (B-C-dots) decorated C 3 N 4 (C 3 N 4 /B-C-dots) catalysts were fabricated through the surface deposition. The benefits from integration of B-C-dots and C 3 N 4 are four folds: (i) increasing surface area; (ii) improving visible light absorption; (iii) promoting the transfer of photoinduced carriers; and (iv) reducing the recombination of photoinduced carriers. The optimum photocatalytic activity of B-C-dots/C 3 N 4 for Rhodamine B (Rh B) (or tetracycline hydrochloride (TC)) degradation was about 7.21 (6.56) and 4.80 (4.35) times higher than that of C 3 N 4 and C-dots/C 3 N 4 , respectively, exhibiting both remarkable stability and repeatability. Moreover, enhanced photocatalytic activity of C 3 N 4 /B-C-dots could also be attributed to the type-II heterojunction formed between C 3 N 4 and B-C-dots caused by B doping. [ABSTRACT FROM AUTHOR]

Highly Li+-conductive HfNb24O62 is explored as a new intercalation-type niobium-based oxide anode material for superior Li+ storage. HfNb24O62 owns a Wadsley–Roth shear structure with a large unit-cell volume, leading to a large Li+ diffusion coefficient. HfNb24O62 shows a large capacity, safe operating potential, high rate performance and good cyclability. [ABSTRACT FROM AUTHOR]

Using aniline as monomer, ammonium persulfate as initiator, ZnCl2 and FeCl3 as metal sources, ZnFe-PANI catalyst precursor was prepared by one-step in-situ chemical polymerization method, and then ZnFe-N-C catalyst was synthesized by high temperature pyrolysis-acidification-secondary pyrolysis. The morphology and structure of the catalyst were characterized by XRD, SEM, Raman and other methods, and its catalytic performance was investigated by the electroreduction reaction of CO2. The results showed that metal doping had little effect on the morphology and structure of N-C materials, but enhanced its structural stability, increased the number of defect sites and active sites, and the area of electrochemical activity, which was conducive to the improvement of reaction performance; When the molar ratio of Zn and Fe was 3 : 1 in the precursor, the obtained sample ZnFe-N-C-3-1 had the best catalytic performance. At an overvoltage of 0.5V, the Faraday efficiency of the CO2 product by electroreduction was as high as 55 %. [ABSTRACT FROM AUTHOR]

Excess sludge, a carbon-rich valuable by-product from wastewater treatment, is utilized as a carbon precursor for synthesizing porous activated carbon. However, improving specific surface area (S BET) is the main challenge for the sludge derived activated carbon (SAC). In this study, the carbonization process was optimized as following: carbonization temperature of 900 °C, heating rate of 10 °C/min, and dwell time of 30 min. Moreover, the residue heavy metals and bound water remaining in the sludge were demonstrated to be important in the pore formation of the SAC. The metals acted as hard template to form the pores in the SAC after the metals were removed by acid wash. The bound water was found to be soft templates for forming pores due to its evaporation during carbonization. A maximum S BET of 1018.8 m2/g was achieved for the SAC when the bound water content was controlled at 2 wt%. Image 1 [ABSTRACT FROM AUTHOR]

Based on both the compatibility principle of similar polymeric structures and the steric interaction, a polyether amine (D2000) modified MOF (UIO-66) was dispersed into an ionic liquid with a polyether structure to form a new porous liquid (called the UIO-66-liquid) at room temperature. This unique UIO-66-liquid showed an outstanding CO2 uptake capacity among the existing porous liquids. [ABSTRACT FROM AUTHOR]

Yolk-shell FeTi coordination complex microspheres were synthesized using a template-free microwave-assisted hydrothermal method. The influences of hydrothermal reaction time and temperature on the morphology and structure were investigated in details. The FeTi coordination complex microspheres with a yolk-shell structure were tested to be an excellent catalyst to transform As (III) to As (V) as well as an adsorbent to effectively remove As (V) ions from solution with an adsorption capacity as high as 235.3 mg g−1 according to Langmuir adsorption model. The FeTi yolk-shell microspheres presented a rapid chemical degradation towards organic materials such as methylene blue (MB) by Fenton reaction without any secondary pollution. The catalytic reaction mechanism of transformation of As (III) and degradation of MB was confirmed by fluorescence spectroscopy. Unlabelled Image • Coordination complex microspheres were prepared by a template-free microwave-assisted method. • These microspheres removed As(III) and As(V) with a capacity as high as 235.3 mg·g−1. • These microspheres rapidly chemically degraded methylene blue. [ABSTRACT FROM AUTHOR]

Herein, we first report a tunable organic magnetoresistance (OMAR) effect in polyaniline (PANI) coated acid treated poly(p-phenylene-2,6-benzobisoxazole) (t-PBO) short fibers. This unique OMAR is interpreted using the paramagnetic nature of PBO molecules combined with the localization length a0 calculated from the wave-function shrinkage model and forward interference model. [ABSTRACT FROM AUTHOR]

• Cobalt nanoparticles anchored porous N-doped carbon nanosheets (Co@PNCS) were fabricated and tested as high-performance cathode catalysts for Li-O 2 batteries. • The capacity as high as 11,329 mAh g−1, with an extended cycle life of more than 120 cycles were reported. • DFT calculations indicated the active Co sites with a more stable binding ability to discharge Li 2 O 2 products than that of the active N sites responsible for this enhancement. Cobalt (Co) nanoparticles anchored porous N-doped carbon nanosheets (Co@PNCS) were fabricated using a facile one-pot pyrolysis route and tested as high-performance cathode catalysts for Li-O 2 batteries. The hierarchical structure was made of cobalt nanoparticles distributed in the crumpled porous carbon nanosheets. Uniformly distributed and exposed cobalt nanoparticles in the PNCS exhibited a higher electrocatalytic activity compared to Co nanoparticles anchored nitrogen-carbon materials (Co-N-C). Density function theory (DFT) calculations based on the interfacial model demonstrated that the active Co sites exhibited a more stable binding ability to discharge Li 2 O 2 products than that of the active N sites, and Li 2 O 2 could be reversibly formed and decomposed during cycling. Owing to optimal loadings of Co nanoparticles (16.03 wt%), the Co@PNCS-2 cathode exhibited a high specific capacity of 11,329 mAh g−1 and extended cycling life of 120 cycles, highlighting the great potential as cathode catalysts for Li-O 2 batteries. [ABSTRACT FROM AUTHOR]

Milled wood lignin (MWL) was isolated from Dendrocalamus sinicus, an abundant bamboo variety in the earth, using Bjorkman method. Elucidation and quantification of the chemical structures for the isolated MWL have been facilitated by employing FT-IR and NMR techniques. The obtained results showed that the MWL consists of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, indicating it as grass type (HGS) lignin. There is no significant change in structure (i.e. cleavage at α-O-4′ and β-O-4′ linkage) was observed. NMR techniques indicated that the isolated lignin was rich in β-O-4′ aryl ether substructures and syringyl (S) units. Furthermore, the sufficient understanding of the chemical structure of the lignin benefits their effective utilization towards the production of renewable biomass and biofuels. [ABSTRACT FROM AUTHOR]

Although polyaniline (PANI) demonstrates a great potential as high performance pseudocapacitor materials for supercapacitors, poor cycle stability due to structural instability is the major hurdle for practical applications. Therefore, designing PANI-based supercapacitors with structure matching performances is highly desirable. In this study, three-dimensional (3D) core-shell Fe 3 O 4 /PANI coaxial heterogeneous nanonets were rationally fabricated via magnetic field induced self-assembly and in situ polymerization. The as-prepared Fe 3 O 4 /PANI nanonets were successfully employed as supercapacitor electrode materials. With the magnetic field derived nanochains from Fe 3 O 4 microspheres as the framework for PANI growth and strain buffer support and the PANI nanofibers as the electrochemically active part, these nanonets realized high specific capacitance, long cycling life, and good rate capability. To be more specific, Fe 3 O 4 /PANI nanonets displayed a specific capacitance of 620 F g-1 at 1.0 A g-1 in 1.0 M H 2 SO 4 solution and capacitance retention of 85% after 2000 cycles at 2.0 A g-1. Compared to other Fe 3 O 4 /PANI hybrids, the obtained better electrochemical performances of these Fe 3 O 4 /PANI nanonets were a result of the complementary contributions of both componential structures in the designed composite electrode. The strategy renders a possibility for using metallic oxide as the favorable support for conducting polymers to effectively store energy. Image 10367 • Fe 3 O 4 /PANI coaxial nanonets were fabricated via MFI self-assembly and in situ polymerization. • These Fe 3 O 4 /PANI nanonets displayed high specific capacitance of 620 F g-1 at 1.0 A g-1. • A capacitance retention of 85% was maintained after 2000 cycles at 2.0 A g-1. [ABSTRACT FROM AUTHOR]

For effective hydrogen generation with remarkable durability, carbon nanotubes (CNTs) grown on Ni nanofibers and their post hydroxylation treatment engendered active Ni nanofiber catalysts an efficient decomposition of hydrous hydrazine with a turnover frequency (TOF) of 19.4 h−1 and an activation energy down to 51.05 KJ mol−1. [ABSTRACT FROM AUTHOR]

Development of polymer based mid-wavelength infrared (MWIR) optics has been limited mainly due to high optical loss of organic polymers used in general optical components. In this study, a MWIR polarization grating based on a sulfuric polymer poly(sulfur-random-(1,3-diisopropenylbenzene)) with a low loss in the MWIR range was fabricated using a simple two-step process: imprint and metal deposition. Fourier-transform infrared (FTIR) spectroscopy measurement showed that this polymeric MWIR polarizer selectively transmitted the polarized IR in transverse magnetic (TM) mode over the transverse electric (TE) mode at normal incidence. The measured extinction ratios (η = The ratio of transmissions in TM and TE) were 208, 176, and 212 at the wavelength of 3, 4, and 5 μm, respectively. The computational simulation and analytical model confirmed that the enhanced TM transmission efficiency and η followed a Fabry-Pérot (FP) resonance mode within the created sulfuric polymer film. This polymeric MWIR polarizer demonstrated a great potential for broader applications in IR photonics to realize low-cost and durable optical components. Image 102 • The first polymer-based mid-wavelength infrared linear polarizer was built with sulfuric polymer film. • Current mid-wavelength infrared polarizer optical elements are based on expensive and fragile inorganic materials. • Transmission and extinction ratio are comparable to commercial products. • Both computational simulation and analytical model confirmed the enhanced transmission efficiency and extinction ratio. • Advantages of the polymeric material allow low-cost and scalable manufacturing. [ABSTRACT FROM AUTHOR]

Graphical abstract An advanced multifunctional electrocatalyst is synthesized by combining Ti 3 C 2 T x MXene nanosheets and melamine-cyanuric acid (MCA) supramolecular aggregates for the first time, further calcinated into the TiO 2 C@CN x nanosheets at differently high temperature. The synergistic effect among different components endows the as-synthesized nanocomposites with multiple functions to catalyze the HER, OER, and ORR in alkaline media. Highlights • A novel nanocomposite of TiO 2 -encapsulated carbon-nitride derived from the Ti 3 C 2 T x and melamine-cyanuric acid. • Synergistic effect among the Ti core, nitrogen-doped graphene-like support, the oxygen vacancies and the porous nanostructure. • Integration good electrocatalytic ability toward HER, OER, and ORR. • Efficient and stable multifunctional electrocatalyst for overall water splitting and Zn-air batteries. Abstract An advanced trifunctional electrocatalyst based on a series of composites composed of TiO 2 -encapsulated carbon-nitride (CN x) (denoted as TiO 2 C@CN x) is developed, which is derived from the Ti 3 C 2 T x and melamine–cyanuric acid calcinated at different temperatures. Among the series of TiO 2 C@CN x nanosheets, the TiO 2 C@CN x,950 (obtained by calcination at 950 °C) hybrid exhibits robust trifunctional electrocatalytic activity toward the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) by combining the excellent electrochemical activity of the graphene-like nanostructure and the high electrocatalytic performances of TiO 2 nanoparticles. When TiO 2 C@CN x,950 is used as the electrocatalyst for water splitting, a current density of 10 mA cm−2 (E j = 10) is achieved at a low cell voltage of 1.50 V vs. reversible hydrogen electrode. Meanwhile, the overall oxygen activity of the TiO 2 C@CN x,950 exhibits good reversible oxygen reaction, giving a small potential difference between the E j = 10 for OER and the half-wave potential for ORR (0.75 V). Moreover, a simply equipped Zn-air battery is assembled using a homemade cathode, showing open-circuit potential of 1.344 V, which also can supplied an electrical power and produced H 2 at the cathode and O 2 at the anode. Consequently, this work can pave a path for developing multifunctional electrocatalysts for water spitting and liquid Zn–air battery. [ABSTRACT FROM AUTHOR]

Low photocatalytic efficiency of visible light and fast recombination of photo-generated carriers are two challenges facing the applications of photocatalyst sterilant zinc oxide (ZnO). Meanwhile, both light and dark photocatalytic activities are important. It is of great theoretical and practical significance to construct a day-night photocatalytic antibacterial material, which is beneficial to the effective use of energy and to tackle the limitation of using photocatalytic bacteriostat. ZnO nanoflowers decorated vanadium pentoxide (V 2 O 5) nanowires heterojunction (ZVH) was firstly fabricated using a facile water-bathing method. The designed ZVH structure efficiently produced abundant reactive oxygen species (ROS) in both light and darkness. It yielded 99.8% and 99.0% of antibacterial rate against S. aureus due to oxidative stress induced by ROS in light and darkness, respectively. The generation of ROS played a major role in the antibacterial activities against S. aureus under both light and dark conditions. The prepared ZVH with improved antibacterial properties provides an alternative for day-night antibacterial agents. [ABSTRACT FROM AUTHOR]

An efficient hydrogen evolution reaction (HER) depends essentially on high-performing electrocatalysts. The aggregation of catalysts normally deteriorates their activity and stability. In this study, a two-step route was used to synthesize surface intercalated well-dispersed spherical MoS2xSe2(1−x) nanocatalysts. The resulting catalysts present a highly active and stable performance towards the HER with an overpotential of −143 mV at 10 mA cm−2, and a Tafel slope of 53.8 mV dec−1. The mechanism for the enhanced HER was analyzed and was attributed to three factors: (i) large numbers of defects and edge active sites arising from the coexistence of S and Se elements; (ii) enhanced electric conductivity arising from the phase transition from the semiconducting 2H-phase to metallic 1T-phase during the intercalation process; and (iii) enlarged contact areas between active sites and electrolyte caused by the increased surface roughness due to the surface intercalation. This work not only deepens our understanding of the improved HER performance of surface intercalated catalysts, but also provides novel strategies for preparing durable electrocatalysts through surface engineering. [ABSTRACT FROM AUTHOR]

In this work, a unique high negative permittivity is observed in the carbon nanosphere (CNS) supported nanosilver-polydopamine (PDA) metacomposites (called CNS-PDA/Ag). The CNS possesses a uniform spherical structure (average diameter of about 200 nm) with a bridge to link CNS together. The Ag nanoparticles are observed to be uniformly deposited on the surface of CNS-PDA core-shell structures with an average diameter of around 10–20 nm. Both impedance and optical band gap results confirm that the CNS-PDA/Ag metacomposites can form a conductive network pathway for further improving their electrical conductivity (about 1 and 2 magnitudes higher than that of CNS and CNS-PDA, respectively). With the support of CNS, the enhanced high negative permittivity observed in the CNS-PDA/Ag metacomposites (about −6.1 × 105) compared with CNS (around −1.2 × 105), CNS-PDA (around 2.5 × 104), and PDA/Ag (around 2.0) is ascribed to uniform decoration of PDA and Ag nanoparticles, induced electric dipole polarization, excellent electrical conductivity as well as anisotropy in dielectric and electrical properties of CNS, PDA, and Ag. The negative permittivity and positive reactance demonstrate an inductance character of the CNS-PDA/Ag metacomposites. This work opens up a new strategy for design and development of metacomposites. Image 1 [ABSTRACT FROM AUTHOR]

A polyvinyl butyral (PVB)/graphene oxide (GO) nanocomposite coating was prepared via spin coating method to improve the anticorrosion ability of aluminum alloy. Poly (methylhydrosiloxane) (PMHS) has been innovatively applied as anti-corrosion coatings of aluminum substrate owing to its hydrophobicity. The properties of the coating were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and other methods. Meanwhile, the corrosion resistance of the coating in 3.5 wt% NaCl solution was estimated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The SEM observations showed that the coating was uniformly distributed on the surface of aluminum. EIS tests showed that the coating had a remarkable anticorrosive effect on the metal surface. Compared with bare aluminum, the low frequency impedance modulus improved three orders of magnitude, reaching 107 Ω cm2. The polarization curve showed that the corrosion current density (I corr) decreased more than three orders of magnitude, reaching 7.8 × 10−9 A cm−2. The long-term immersion experiment indicated that the coating could effectively protect the aluminum for up to 1200 h. This study provides a facile way of using polymer nanocomposites to tackle the corrosion of aluminum alloy for industrial applications. Image 10077 • Poly (methylhydrosiloxane) (PMHS) has been applied as GO/PVB composite coating. • The influence of the GO content on the corrosion resistance was studied. • The long-term corrosion resistance of the composite coating was tested. [ABSTRACT FROM AUTHOR]

Nanocomposites with a well-defined sandwich-like nanostructure were prepared via in situ growing NiCo-layered double hydroxide nanosheets with tunable Ni/Co ratios on reduced graphene oxide (rGO). Electrochemical impedance spectra and N2 adsorption/desorption isotherms confirmed that these sandwich nanostructures effectively promoted charge transport and enlarged the specific surface area. The nanocomposites with Ni : Co = 2 : 1 exhibited a maximum specific capacitance of 2130 F g−1 at 2 A g−1, excellent rate capability (72.7% retention at 15 A g−1), and cycling stability. Asymmetric supercapacitors were assembled with these nanocomposite cathodes and rGO as a negative electrode (anode), and demonstrated an energy density of 34.5 W h kg−1 at a power density of 772 W kg−1, while maintaining a capacity retention of 86.7% after 10 000 cycles at 5 A g−1. The robust electrochemical properties indicate the composites as promising electrodes for electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

2D transition metal dichalcogenides with a formula MoX2 (X=S or Se) have been explored as promising earth‐abundant catalysts for hydrogen evolution reaction (HER), especially those with 1T phases. Theoretical calculations and experiments have indicated that optimal catalytic performance can be achieved by regulating the atomic ratio of S and Se in Mo(S1‐xSex)2. However, the preparation of 1T phase Mo(S1‐xSex)2 is challenging because of the differences of S and Se elements. Here, we propose a facile and effective hydrothermal method for the production of 1T/2H Mo(S1‐xSex)2, with which products with various x values are prepared. The as‐prepared Mo(S1‐xSex)2 samples give a low Tafel slope of 42.8 mV dec−1 (x=0.25), and an overpotential of 161 mV (x=0.5), which are state‐of‐the‐art among the tremendous MoX2 works. The excellent electrocatalytic performance is derived from the coexistence of S and Se atoms which reduces the reaction potential energy, and the presence of the 1T phase which improves the conductivity. Additionally, the ratio of 1T phase to 2H phase of Mo(S1‐xSex)2 is found controllable over reaction temperature. [ABSTRACT FROM AUTHOR]

Abstract In this study, porous one-dimensional (1D) CoO nanobelts and two-dimensional (2D) CoO nanoplates were successfully fabricated by calcining single crystalline cobalt carbonate hydroxide hydrate - Co(CO 3) 0.5 (OH)·0.11H 2 O nanobelts and nanoplates obtained using a solvothermal method. Solvents applied in the reaction significantly affected the shape and size of Co(CO 3) 0.5 (OH)·0.11H 2 O. Belt-like Co(CO 3) 0.5 (OH)·0.11H 2 O crystals can be easy to turn into to plate-like by adjusting the volume ratio of ethylene glycol (EG) to water. The as-prepared porous CoO nanobelts, when used as the supercapacitor electrode materials, exhibit a higher specific capacitance of 1178 F g−1 at 1 A g−1 than porous CoO nanoplates. Asymmetric supercapacitor (ASC) based on CoO nanobelts and aqueous electrolyte also show more excellent electrochemical performance, e.g., higher energy density (68.5 Wh kg−1 at 850.0 W kg−1) and long-term cycling ability. Highlights • Solvent proportion determine the shape and size of CoO precursors. • Controlled oriented attachment and Ostwald ripening by adjusting a mixed-solvent. • CoO nanobelts show a higher supercapacitor performance than CoO nanoplates. • CoO nanobelts//AC achieves an ultrahigh energy density of 65.2 Wh·kg−1. [ABSTRACT FROM AUTHOR]

Abstract We synthesize a series of cobalt species combined with carbon nanotubes loaded onto graphene-like titanium carbide (CoO x -N C/TiO 2 C), which are derived from bimetallic CoZn-based zeolitic imidazolite framework and Ti 3 C 2 T x MXene composite (CoZn-ZIF/Ti 3 C 2 T x). The as-result CoO x -N C/TiO 2 C composites are further explored as the trifunctional electrocatalysts for hydrogen evolution reaction, oxygen reduction reaction, and oxygen evolution reaction. Among composites containing different Ti 3 C 2 T x dosages, the CoO x -N C/TiO 2 C(22.7%) exhibits the most excellent electrochemical conductivity. When CoO x -N C/TiO 2 C(22.7%) is used as the electrocatalyst for water splitting, a current density of 10 mA cm−2 (E j = 10) is achieved at a low cell voltage of 1.45 V. Meanwhile, the overall oxygen activity of the CoO x -N C/TiO 2 C(22.7%) shows a small potential difference (0.72 V) between the E j = 10 for oxygen evolution reaction and the half-wave potential for oxygen reduction reaction. The outstanding catalytic performances are mainly attributed to the synergistic effect among the different components of the CoO x -N C/TiO 2 C composite, such as carbon nanotube content that is in favour of electronic mobility, hierarchical porosity that facilitates mass transport, and uniformly dispersed cobalt, cobalt oxide, and titanium dioxide active sites in the carbon framework. Consequently, the present work will shed light on the application of other metal-organic framework- and carbon-based electrocatalysts for energy conversion. Highlights • A novel catalyst fabricated by calcining a composite of CoZn-ZIF and MXene. • The synergistic effect in Co species, CNTs, TiO 2 nanoparticles and carbon framework. • Highly efficient trifunctional electrocatalysts for ORR, HER and OER. [ABSTRACT FROM AUTHOR]

Abstract: Layered transition metal sulfides (LTMSs) have tremendous commercial potential in anode materials for sodium‐ion batteries (SIBs) in large‐scale energy storage application. However, it is a great challenge for most LTMS electrodes to have long cycling life and high‐rate capability due to their larger volume expansion and the formation of soluble polysulfide intermediates caused by the conversion reaction. Herein, layered CuS microspheres with tunable interlayer space and pore volumes are reported through a cost‐effective interaction method using a cationic surfactant of cetyltrimethyl ammonium bromide (CTAB). The CuS–CTAB microsphere as an anode for SIBs reveals a high reversible capacity of 684.6 mAh g−1 at 0.1 A g−1, and 312.5 mAh g−1 at 10 A g−1 after 1000 cycles with high capacity retention of 90.6%. The excellent electrochemical performance is attributed to the unique structure of this material, and a high pseudocapacitive contribution ensures its high‐rate performance. Moreover, in situ X‐ray diffraction is applied to investigate their sodium storage mechanism. It is found that the long chain CTAB in the CuS provides buffer space, traps polysulfides, and restrains the further growth of Cu particles during the conversion reaction process that ensure the long cycling stability and high reversibility of the electrode material. [ABSTRACT FROM AUTHOR]

NiCoAl layered double hydroxides (NiCoAl-LDHs) with different morphology, structure, size and pseudocapacior properties have been prepared by tuning the ratio of metallic elements via a hydrothermal method. The optimized element proportion of 2D NiCo 2 Al-LDH consisting of hexagonal nanosheets delivers a significantly enhanced specific capacitance 2369.4 F g −1 at a current density of 1 A g −1 . A circle-like growth mechanism is proposed to explain the formation of the 2D NiCo 2 Al-LDH structures. Its 2D structure and the synergistic effect of three metallic elements assure its high electrochemical performance. An asymmetric supercapacitor (ASC) based on NiCo 2 Al-LDH exhibits an ultra-high energy density of 91.0 Wh kg −1 at a power density of 758.2 W kg −1 as well as long-term stability (92% of its initial capacitance retention at 8 A g −1 over 5000 cycles), outperforming most of LDH and metal oxides ASCs. [ABSTRACT FROM AUTHOR]

Hierarchical hybrid electrodes CoO@MnO 2 nanosheet@nanosheet arrays (NNAs) for high-performance supercapacitors are designed and grown on a 3D nickel foam by a simple two step solution method combined with a post annealing treatment in Ar gas. The MnO 2 nanosheets can grow directly on the CoO precursor nanosheet arrays without any pretreatment, and its thickness on the CoO NAs can also be tailored by adjusting the hydrothermal time. The NNAs with the elegant synergy between CoO and MnO 2 lead to a highly enhanced areal capacitance (2.40 F cm −2 at 2.0 mA cm −2 , with a wide potential window of 0.8 V). We further fabricated asymmetric supercapacitor device based on the CoO@MnO 2 NNAs and active carbon, which achieved a high-energy density of 1.4 mWh cm −3 at a power density of 9.6 mW cm −3 , a high power density of 192.3 mW cm −3 at 0.7 mWh cm −3 and good cyclic stability. [ABSTRACT FROM AUTHOR]

A new core-shell nanostructure of CoO@MnO 2 nanowire@nanosheetarrays(NNSs) was designed and directly grown on a 3D nickel foam by a simple two step solution method combined with a post annealing treatment in Ar gas. The MnO 2 nanosheets can grow directly on the CoO precuor nanowires without any pretreatment, and its thickness on the CoO nanowire arrays (NAs) can also be tailored by easily adjusting the second step hydrothermal time. When acting as a electrochemical supercapacitor, the CoO@MnO 2 NNAs delivers a highly enhanced specific capacitance of 3.03 F cm −2 (about 1515 F g −1 ) with a wide potential window of 0.8 V at 2.0 mA cm −2 , which is superior to most reported Co 3 O 4 based core-shell NNAs supercapacitive electrodes. An asymmetric supercapacitor devices based on these CoO@MnO 2 NNAs and aqueous electrolyte showed with a high-energy density of 0.37 mWh cm −2 at a power density of 1.7 mW cm −2 , a high power density of 34.4 mW cm −2 at 0.20 mWh cm −2 and a long-term cycling ability, implying its great potential application in high-performance electrochemical supercapacitor. [ABSTRACT FROM AUTHOR]

We present a facile one-step solvothermal approach for in situ growth of ultradispersed nickel cobalt sulfide (NiCo 2 S 4 ) nanoparticles on the graphene (GR) sheets without adding any surfactant. When acting as an electrochemical supercapacitor electrode material, the NiCo 2 S 4 @GR delivers a highly improved specific capacitance of 1708 F g −1 at a current density of 1.0 A g −1 , compared with that of free NiCo 2 S 4 (950 F g −1 ). The performances of NiCo 2 S 4 @GR electrode material can also be optimized by carefully tailoring the amount of each ingredient NiCo 2 S 4 and GR in the nanocomposites. Asymmetric supercapacitor devices based on these NiCo 2 S 4 @GR nanocomposites and aqueous electrolyte showd a long-term cycling ability with a high-energy density (68.5 Wh kg −1 at 850.0 W kg −1 ) and a high-power density (17.0 kW kg −1 at 37.7 Wh kg −1 ), implying its great potential application in high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

• An experiment was built to simulate leaks in an industrial scale experimental pipeline. • The effects of orifice size, pipeline pressure, and liquid flow speed were investigated. • An artificial neural network model was developed for leaks prediction. Water pipeline leakage is a common and significant global problem. In-pipe inspection based on hydrophone is one of the most direct, accurate, and reliable solutions for leak detection and recognition. In this study, a scheme of in-pipe detector was designed to pick up and identify acoustic signal due to leak. To investigate the characteristic of acoustic signal, an experimental platform was built to simulate the leaks and obtain acoustic signals under different leak conditions in an industrial scale water pipeline. Because a decreased pressure as leak has an unstable fluctuation in time domain, the frequency composition of the signal was analyzed in frequency domain, and then the change of frequency amplitude can be referenced to recognize the leaks. Moreover, the effects of leak size, pipeline pressure, and water flow rate on the characteristic of acoustic signal were investigated. The results show that the signal's intensity under leak conditions are significantly higher than that of no leak case, and it will increase as the increased leak size; the signal intensity under no leak case will increase with the growth of pipeline pressure; the flow velocity has little effect on the signal intensity. To increase the recognition accuracy, an artificial neural network model was developed for the leak prediction, and 18 cases through additional tests were selected to validate the accuracy of model. Comparing experimental and prediction results, maximum relative error is within 10.0%. It indicates that the prediction model has a reasonable accuracy for the leak recognition. [ABSTRACT FROM AUTHOR]

• Cu 2−x Se plates with dominant (111) can reduce the migration energy for Na ion. • Cu 2−x Se plates deliver 377.6 mAh g−1 at 0.1 A g−1 and 315.3 mA h g−1 at 10 A g−1. • High pseudocapacitive contribution ensures its high-rate performance. • Excellent capacity retention of 93.2% after 1000 cycles at 5 A g−1. [Display omitted] The traditional views hold the conversion and intercalation compounds without nanostructure used in ion batteries could not afford high-rate performance. This study demonstrated a bulk material of hexagonal plate-like Cu 2−x Se with exposed (111) plane exhibits an ultrahigh rate performance without any assistance of high conducting graphene or carbon nanotube, et.al. The bulk Cu 2−x Se plates, used as the anode of sodium ion battery, deliver a high capacity of 377.6 mA h g−1 at 0.1 A g−1 and maintain a capacity retention rate of 83.5% at 10 A g−1, as well as a long cycle life of 93.2% after 1000 cycles at 5 A g−1. Density functional theory analysis confirms that the (111) faceted Cu 2−x Se plates with reduced migration energy for Na ion across the Cu 2−x Se can enhance its electrochemical reaction kinetics. Moreover, the detailed Na ion insertion/extraction mechanism was demonstrated by combining the in situ and ex situ measurement technologies. [ABSTRACT FROM AUTHOR]